Commonly, angles of a headrest of a car seat or a sofa can be adjusted to meet the requirement of the customers. One of the achievement manners is to set a hinge connected with the headrest in the car seat or sofa, and the headrest rotates with the hinge so as to change the angle between the headrest and the car seat or sofa. As such, the customer can adjust different tilting angles of the headrest according to his actual requirement to obtain a comfortable feeling.
In order to achieve the above functions, the structure of this hinge needs to meet two requirements: First, relative to the seat or the sofa, the hinge can drive the headrest to rotate to a satisfactory position in an angle range; secondly, when the headrest has been adjusted to the satisfactory position, and then the headrest can be fixed by the hinge to prevent from further rotating.
In the prior art, the hinge provided between the headrest and the seat or the sofa has engaging teeth and engaging positions therein, by which the headrest can rotate and be fixed, the engagement of the engaging teeth and the engaging positions limits the headrest to rotate only in one direction, that is, the headrest just can rotate forward relative to the seat or the sofa but is forbidden to rotate reversely so as to fix the headrest. If the headrest is wanted to be adjusted reversely, firstly the headrest rotates forward to the very end, thereby the engaging teeth disengage from the engaging positions, and then the headrest can be adjusted reversely.
It is thus clear that although this conventional hinge has angle adjustment function, but can not rotate reversely at any position when you want to adjust it back, the operation is complicated and time consuming.
Thus it's necessary to provide a hinge that can rotate reversely at any position, and the operation is simple and convenient.